Micro-Hall Magnetic Sensors: Physics, Technologies and Applications
This chapter describes the Hall plates with the planar dimensions from micro-meter to deep sub-micrometer range. In the theoretical part, the physical phenomena in such micro-devices are described. Scaling down the dimensions of a Hall plate, the prevailing mechanism of electron transport changes. In macroscopic devices stationary transport takes place. Depending on the device size and applied voltage, the drift velocity of carriers may be linearly dependent on the voltage or saturated. Scaling down further, the device enters the non-stationary transport range, where velocity overshoot and ballistic transport occur. In each regime magnetic sensitivity and noise of the device are estimated. In the experimental part, a review of the published results on the technologies, performance, and applications of micro-Hall devices is given. In summary, scaling down a Hall sensor brings about a degradation of its basic characteristics. On the other hand, micro-Hall devices open the way to applications where high spatial resolution is necessary, like in scanning Hall probe microscopy.
Keywords: Magnetic sensors, micro-Hall, scaling down, sensitivity, noise, resolution.
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